engine and drivetrain Engine Cooling Fans: Differences

[PaulTWinterton]

The smaller (360mm) fan is a SOFT plastic.  The tropical (400mm) fan is a STIFF plastic.   I'm not sure if it was intentional to make the smaller fan so bendable.  Were they always so pliable?

The smaller fan blades bend forward as you accelerate the engine.  I calculate approx. 1/2" @ 5000rpm.  Which is ok with a stock rad, but any alteration to the hangers (common in re-coring) or re-coring with a 3-core can cause grief. 

Other than deteriorated engine/trans mounts, I believe that's why we see so many chipped or broken fans.  They bend.  They hit the lip of the upper tank  first, then distort,  and finally break or bite into the core.

The larger tropical fan bends very slightly and has a structural integrity that resists bending beyond a certain pressure.

I opted for the STIFF larger fan and a properly hung 2-core rad with more cores to the inch. 

[Mike Self]

The "stiff"er--larger fans also break.  The one on my '73 was down to one full length blade (and it had a bite out of it) and the rest no more than a few inches long--one was a half-inch stub.  Oddly enough I was never aware when the blades broke off, they did no damage when they did break, and the car didn't overheat.  I drove to Vintage and back on that fan (with a good spare in the trunk just in case...)

 

I suspect all the fans (including the small 4 blade fan as used on the early cars--inadequate for the US) get brittle with age and eventually disintegrate.  I've been running a big fan along with a three row core radiator since around 1987 with no clearance problems--tight but no touching...

 

mike

[PaulTWinterton]

I've been running a big fan along with a three row core radiator since around 1987 with no clearance problems--tight but no touching...

 

I guess what I'm trying to say is if it's "tight but not touching" beware using a small fan.  They bend forward dramatically on acceleration.  My small fan was close but not touching and a few revs above 4000 put the fan into the 3-core radiator.   Luckily it only scarred the fins.

[Sal Savino]

Mike:. You indicated that the 4 blade fans were used on the early 2002s. Do you have an idea on when the switch to the 5 blades occurred?

Thanks

[Mike Self]

Sal, I suspect the switch came fairly early--probably sometime in 1970, or shortly after dealers started fitting aftermarket A/C units on 2002s and discovered they overheated.  The parts book isn't real clear on this, but it may have been at VIN 1668338.  

 

I switched over to a larger fan sometime in the mid-70s, as my car always ran a little hot in the summer (temp needle at about 2-2:30). The larger fan brought it back to 3 o'clock.  Then I fitted a staggered row, two row core radiator (no more capacity, but the cooling tubes are not aligned behind one another so are better exposed to the air) and I was able to go back to the original small fan (more for authenticity than anything else) and have had no problems even on long trips in hot weather.  Go figure.  

 

cheers

mike

[jgerock]

The fan in my 69 (new 5 blade) has already been chipped by rubbing against the top tank lip of the 3 row SI garage radiator.  I originally  thought this was due to the nose replacement, but now think the side mounts on the radiator were welded on a little to the back (since there is clearance at the front).

Edited December 3, 2016 by jgerock